First, samples for qualitative investigations tend to be small, for reasons explained later in this article. Even if a representative sample was desirable, the sampling error of such a small sample is likely to be so large that biases are inevitable. Secondly, for a true random sample
to be selected, the characteristics under study of the whole population should be known; this is rarely possible in a complex qualitative study. Thirdly, random sampling of a population is likely to produce a representative sample only if the research characteristics are normally
distributed within the population. There is no evidence that the values, beliefs and attitudes that form the core of qualitative investigation are normally distributed, making the probability approach inappropriate. Fourthly, it is well recognized by sociologists1 that people are not equally good at observing, understanding and interpreting their own and other people's
behaviour. Qualitative researchers recognize that some informants are 'richer' than others and that these people are more likely to provide insight and understanding for the researcher. Choosing someone at random to answer a qualitative question would be analogous to randomly
asking a passer-by how to repair a broken down car, rather than asking a garage mechanic—the former might have a good stab, but asking the latter is likely to be more productive